a = 4
b = 5

# 第一种
c = 0
c = a
a = b
b = c
print("第一种：a=%d, b=%d" % (a, b))
a = 4
b = 5
# 第二种
a = a + b
b = a - b
a = a - b
print("第二种：a=%d, b=%d" % (a, b))
# 第三种
a = 4
b = 5
a, b = b, a
print("第三种：a=%d, b=%d" % (a, b))
